@yotsuya: Again, I respectfully disagree.
AotC was definitely shot in 1440x800.I think the important part is this:
Since SW2 was to be displayed as 2.35:1, and Panavision were not able to come up with the promised Anamorphics to work with a Prism-splitter 3-CCD camera, the movie was shot letterboxed, so the master images were only 1440 x (about) 800.
Lucas didn’t plan to use a HDW-F900, but a ‘Panavised’ one (HDW-F900F). But Panavision didn’t deliver in time, so Lucas had not other choice than cropping his shots.
Furthermore, HDCAM SR tape format was not yet available, so he had to use a ‘bastardized’ HDCAM 4:2:2 (instead of 3:1:1, but not SR) limited to 1440x1080.
So the final cropped shots were in 1440x800 (which is still HD).
Some other interesting quotes:
this meant that, unfortunately as is the case with digital masters in general, 1440x1080 would remain 1440x1080 until the end of Time
According to Wikipedia :
The actual resolution of Attack of the Clones is not 2k, but just 817x1440 pixels. This is because the HDCAM format subsamples the 1920 horizontal lines to 1440. The 1080p aspect ratio of the camera only applies when the 16:9 aspect ratio is used. To produce the 2.39:1 aspect ratio, the top and bottom of the image are cropped, reducing detail. This cropping is why Spy Kids 2, (shot with the same camera) looks better then attack of the clones. Spy Kids used the native 16:9 aspect ratio and thus used all the pixels of the camera. (Anamorphic lenses could have allowed the full 1080 lines to be used, but were not available for the HDW-F900.) . --Algr (talk) 19:17, 27 June 2019 (UTC)
(https://en.wikipedia.org/wiki/Talk:Star_Wars:Episode_II%E2%80%93_Attack_of_the_Clones)
And the final word to ILM HD Supervisor Fred Meyers himself :
With the earlier equipment, RGB color from the camera was converted into 4:2:2 YUV format when it was recorded. This format effectively slices the color bandwidth in half because one color value represents more than one pixel. The result is fewer chroma (color) samples than luma (luminance). This chroma sub-sampling combined with spatial sub-sampling effectively reduced HD’s 1920 resolution to 1440 for luma and 960 for chroma.
JEDIT: ChewieLewis is right, most of the movie is CGI, not related to HD cameras.
IIRC, CGI was rendered in 2k (so really no need to scan AotC in 4K, which is the main question here)
The Panavision one was to compress the vertical image so the full 1080 was used. The camera is rated for 1920x1080, not 1440x1080. That was the previous camera. The Panavision lens vertically compresses that 1080 into what ATOC an ROTJ cropped down to 816 (or some sources say 818) giving 262-264 lines more vertical resolution to widescreen film. And yes, the color levels were compromised compared to what came after, but the pixel resolution was not. I did some tests on what impact it would have on each frame if the yellow was horizontally compressed (1/3 of the image) and there is more noise from compression artifacts than there is from doing that. And looking at the image of many films, the yellow layer is the lowest resolution of them (if you study how film is made, there are some interesting tricks that give us what we perceive as full color without giving each of the three colors equal clarity).
And if what you say is true, the evidence should be there in the frames. I isolated a frame that lacks any FX (not easy to do in those two films) and if what you say is true, I should be able to compress any frame to 1440x1080 and expand it back to 1920x1080 and there should be no quality loss. Well, there is quality loss. That process degrades the image in a detectable way. It is not readily apparent to the naked eye, but it is there. I ran the same process on a couple of other images (not from movies) and they show the same level of detail and the same degradation of the image if I compress them the the same way. I don’t see any evidence that the image was reduced to 1440 and expanded while I do see evidence that it wasn’t.
But regardless of the exact resolution of the image that was printed to 35 mm film, in order to get the best result when scanning the film, scanning it at 4k is best. Scanning at the exact resolution of a printed image will result in quality loss. Where if you scan at a higher resolution (and then reduce it properly if needed) it will preserve the quality.